Fort Worth daily gazette. (Fort Worth, Tex.) 1882-1891, 1887-05-01


ridges theory as the most plausible, in
corporated it in his map of the United
States, accompanying the fifth annual
report of the director of the United States
Geological Survey, Washington, D. c.,
1886.
With all these theories in mind, l must
confess that visited the region this sum-
mer win a preconceived idea that l
should find some one of them approx
mately true, and l was greatly surprised
TO find them ell equally erroneous.
TOPOGRAPHIC AND GEOLOGIC CHARACTER
ISTICS
Before proper appreciation Of the re-
latiOns Of the two members of the Cross
Timbers to each other can be arrived at,
it is necessary to briefly review the
salient Typographical features of this pOr-
ton of the state of Texas. The river
drainage Of the state indIca !es the only
general feature in it's topography-a slope
of the surface from northwest to south
east; but even to this feature there are
several important exceptions. For my
own convenience have divided the tOpO-
graphic features Of the state into the fol-
lowing broad areas:
l. The Coast Plain, continuation of
the Topographic features of the gulf
states so far as they represent old out
lines of pOst-CretaceOus sedimentation of
the Gulf of Mexico. Although a portion
of the cretaCeOus strata for a short dis
lance west of it could be classified geolog-
ically with this Coast Plain, its tOpo-
graphic border is made to coincide with
the interior border of the marine tertiary,
the plain being mostly a forest covered
section of country, and at much lower
altitude than the prairie region.
.. The Black Prairie Region. This
constitutes an elongated, triangular region
continuing from Arkansas and Indian
Territory into Northern and Central
Texas, and Immediately adjoining the
foregoing Typographical division on the
west. It's western border follows
a line drawn through Dallas and Austin,
from DenisOn to San Antonio, where it
makes a western detection to the Rio
Grande. Geologically, this region is also
a continuation of the features of the other
gulf states, but beyond it's western edge
the continuity ceases. 1t differs from the
Coastal Plain in being at a much greater
altitude, and consisting almost entirely
of level prairie region. Its altitude is
from $50 to $50 feet.
3. The Central Denuded or Hilly
Region. This area, in itself, embraces
great number of unique and well-marked
topographic features, each Of which is
worthy of a more detailed description
than can be here given. 1t might be called
the "butte" region, the "drOuth" region,
or by any of a dozen local descriptive
names equally applicable to it; but It's gen
eTaI features are all the result of one
great cause, an excessive amount of SUI
pertCial denudation. 1t includes all the
country west of the Black Prairie Region
to the escarpment of the plains, IN the
northwest, and to the traus-PeCOs noun
famous region of the southwest. 1t en-
braces multitude Of geologic fOrma-
tions, but there is in it little or no evil
dence of local disturbance in the strata
It's altitude is generally between $50 and
1000 feet.
l. The Plateau, or Pan Handle Region.
This comprises the northern and most
extensive half of the LlanO EstaCadO, and
is a southern continuation of the great
plains of Kansas.
) The Mountainous or Trans-PeCOs
Region. Most of the country west of the
PeCOs, consists Of highly disturbed,
mountainous areas. The general direC-
ton of the axes of the disturbances IS
parallel with the course OF the PeCOs, the
Rio Bravo, and the SabiDas river in Mex
leo, all which flow nearly due southeast.
heeastern border Of this area crosses the
Rio Grande west of the PeCOs, continues
in Mexico for q distance, but again
crosses the Rio Grande eighteen miles
west of Eagle Pass, and for hundred and
fifty miles it extends along the Texas side
of that river 10 below Laredo, where it
again crosses it into Mexico.
The two belts of the Cross Timbers are
entirely within the third, or Central
Denuded Region, the eastern border OF
the lower timbers Coinciding almost eX-
actly with the western border of the sec
ond Typographical area. The chief geo
logic agency in modifying the surface of
this region, IS before stated, has been
subaeriaI erosion. The only elevation
apparent Is that which is common to the
other areas, and which was due to the
rising of the Rocky Mountain axes. The
denudaJion resulting from the subaeriaI
erosion has been very great, the whole OF
the geologic series, from the recent to far
down into the CarbOniferOus, having been
removed from it's center or place of
greatest denudatiCn. In travelling IN either
direction from the center Il this
region, east or west, and sometimes
south, the geologic formations will be
passed in ascending series, from the car
Ooniferous into the tertiarie5. The de-
mutation is progressing now at rate
probably greater than in any time past,
and the geologic features are being con-
stantly modified by it. The tertiary, if
it ever existed there, has already been
removed from this vast area, snd the
cretaceous is rapidly yielding-iu places
entirely gone. This fact being true, it IS
evident that the Cross Timhers cannot
represent any post-cretaceous sediments
Going from east to west along the line
of the Texas and Pacific Railway, as l
have represented upon the accompanying
profile and geologic section-frOm the
area of the least denudatiOn to that Of the
greatest-let US examine more closely into
THE RELATIONS OF THE STRATA,
and their connection with the present to-
geographic features. The second topo-
graphic area, after passing west Of the
first, or Coast Plain with which l shall
not deal in this paper, is locally known
as the "blaCk WaXy" or "white rock
prairie, two names derived respectively
from the character of the soil and of the
underlying rock. 1t has such topographic,
geologic. and paleontologic resemblance
to the "Rotten limestone" of the other
gulf states, as we'll as direct geographic
continuity, that there is no doubt but that
it, as well as it's Immediately adjacent
strata, is a continuation OF the
same formations from those states.
The underlying rock is soft,
almost structureless, slightly foramini-
ferrous limestone rich in magnesium,
which, on dry exposure, hardens and
bleacnes to a yellow-white and on contact
with moisture readily decomposes and
crumbles. Natural sections wherever eX-
posed by the creeks or rivers,
show that there is gradual
transition from rock to mari and
Il. n.hnr --,,-L- tho ton